D-Penicillamine and salts thereof are well known to be useful in the treatment of Wilson's disease, rheumatoid diseases and cystinuria. Several methods for preparing D-penicillamine and its salts have been already attempted as described in Nature, 151, 107 (1943), Nature, 171, 343 (1953), J. Org. Chem., 37, 2733(1972), and the specifications of British Pat. Nos. 854,339 and 959,817 and U.S. Pat. No. 3,960,940.